There is recognized in the fastening arts the need for a fastener which will rotatably join two relatively thin sheets of metal. These fasteners are often referred to as pivot bearings or thrust bearings. Examples of such structures are shown for example in U.S. Pat. No. 4,582,435 issued to Davis entitled “Pivot Bearing.” Another such device is described in U.S. Pat. No. 5,860,780 issued to Lenac et al. In both cases, a riveting type process is used to flare over either one of the material sheets or a rivet type fastener as depicted in the patent to Lenac et al. Each of these systems has their disadvantages which include the inability to provide a resilient separation between the sheets or to accommodate axial deflection without impairing the relative rotation between the sheets. Furthermore, installation of the Lenac fastener into the sheets can be complicated. Also, in both of these instances, one of the bearing surfaces is necessarily the sheet material itself. This can result in excessive wear, maintenance problems, and failure of the joint. It also limits the sheet material and its surface condition. Joint assemblies which solve this problem are more complicated, three-component systems.
There is therefore a need in the art to join two sheets of relatively thin sheet metal while allowing rotation between them in a manner which is efficient and economical and which also allows for axial deflection and resilient separation between the sheets. There is also a need in the art for a simplified rotatable joint assembly for thin metal sheets in which neither of the sheets is required to be a frictional bearing surface.